EXPLOSIVES IN MINES

Otautau Standard and Wallace County Chronicle, Volume XI, Issue 522, 18 May 1915, Page 7

EXPLOSIVES IN MINES

At last a device has been diecovei**«d to limit an explosion m a coal mine to certain workings, and keep it from spreading to others. The device was discovered by Teffanel, and is now used to a good extent m Germany, and is being tried m the United States. It all hinges on the fact that if you. can cool a body, even an igniting gas, below the point of ignition, it will go out. The most familiar experiment to show this principle is that of the wire and the candle. If a piece of copper wire be twisted into a spiral and one end thrust into a candle flame, the candle will grow dimmer, and finally go out, for the copper wire,' being ''a good conductor, of heat, conducts off the heat faster than it is formed, and thus brings the wick below the point of ignition*. Teffaniel's device is to put up numerous shelves acroes the horizontal tunnels m mince, and to fill these with broken stone* The stone, as the front* of the • explosion, consisting of burning gas, -reaches it, absorbs a great deal # of the heat. It has* been found m actual trials that, the explosion goes on for about 200 ft beyond the, shelves of stone, and then c-eases. The miner's safety lamp, invented by Davy, shows the same principle. It is nothing but an oxdinary wick surrounded with a wire gauze. An explosive mixture will, of course, seep through the gauze, and become ignited by the flume ; but it will not explode beyond the gauze, on account of . the fine heat-, conducting, qualities of the latter. The same thing is seen m the laboratory when a flame .is held under a wire netting. It will not -appear .above the netting. If lighted "above tlie . netting, it will not ap-pear-below it. — 'New York Sunday Magazine.'